1. Field of the Invention
The present invention relates to loudspeaker rigging systems and more particularly to rigging hardware for suspending a stacked array of loudspeakers of a sound reinforcement system at a predetermined location relative to an audience. The present invention has particular application in rigging a stacked array of loudspeakers wherein a vertical splay between loudspeakers is desired to achieve a desired coverage and acoustic performance.
2. Description of Related Art
Sound systems for large venues typically involve the suspension or “flying” of stacks of loudspeakers in vertical arrays to achieve a desired acoustic output and coverage for a large audience. Such vertical stacks of loudspeakers are typically suspended and held together by rigging systems which may be attached to rigging hoists which position the stack at a desired elevation and location, typically above or in the vicinity of a performance stage. A flown stack of loudspeakers can include many speaker boxes and the rigging system for flying the stack must be strong enough to support the weight of the large stack. Such rigging systems generally involve the use of metal side frame elements secured to the speaker boxes that can be used to link the speakers together in a stacked arrangement and to lift the stack to an overhead flying position.
Typically, the individual speaker boxes of a vertical stack of loudspeakers held by a rigging system will have to be adjusted to meet the requirements of a particular application. Setting the proper angle between speakers, or “splay angle,” can be critical to achieving desired acoustic performance and minimizing interference between the acoustic output of speakers in the stack. Splay angles are adjusted by adjusting the linkages between the rigging frames of the stacked speakers to create a desired angle. One such adjustment method is disclosed in U.S. Pat. No. 6,640,924 issued Nov. 4, 2003 to Ian Messner (the “Messner patent”). The Messner patent discloses a rigging system wherein the splay angle is adjusted by a cam plate that pivotally extends down from the bottom front end of the side frame of one loudspeaker to engage the top front end of the side frame of the loudspeaker directly below. To set the splay angle, the cam plate must be manipulated into a cam plate receiving channel in the top of the underneath side frame and pinned when the desired cam hole is aligned with the pin hole in the subjacent frame.
An improved rigging system is disclosed in U.S. Pat. No. 7,693,296 issued Apr. 26, 2010 to John Monitto (the “Monitto patent”). The Monitto patent discloses a side frame for a loudspeaker and associated pivot and splay adjustment links. The pivot and splay adjustment links are maneuverable using a gripping structure and are downwardly extendible from stow channels in the bottom corner regions of the frame structure into receiving channels in top corner regions of the frame structures of subjacent loudspeakers. The bottom extended end of the splay adjustment link includes an array of pin holes which can be selectively matched with one pin hole in one or more rows of pin holes provided in the bottom corner region of the side frame thereby permitting adjustments of the splay angle over a range of angles. This system requires that each pair of loudspeakers be interlinked one at a time by releasing the links into the receiving channel in the frame structure of the subjacent loudspeaker, pinning them in place, and then using a hoist to lift the top loudspeaker or stack of loudspeakers to line up the pin holes in the splay adjustment link with the pin holes in the bottom corner region of the side frame. This can not only time be consuming, but becomes progressively more difficult as the number and added weight of rigged loudspeakers in a stack of loudspeakers increases. The increasingly heavy stack of loudspeakers can bounce when lifted by a rigging hoist making it difficult for the pin holes in the side frames to align with the pin holes in the links and increasing the potential for physical injury to the equipment and to riggers.
There is thus a need for a rigging system for loudspeakers that does not require lifting and precisely aligning each pair of loudspeakers in a stack of loudspeakers that is being interlinked. There is also a need for a rigging system having links in side frames that can be used for interlinking adjacent loudspeakers by moving only the links rather than all the loudspeakers in a stack of loudspeakers above the loudspeaker being linked. There is also a need to provide a rigging system that is relatively easy to assemble and that has small incremental splay angle adjustment capabilities.